#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#ifdef __linux__
#include <sys/socket.h>
#elif _WIN32
#include <winsock2.h>
#endif

void error_handling(char* message)
{
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}
#ifdef __linux__
int client(int argc, char * argv[])
{
    int sock;
    struct sockaddr_in serv_addr;
    char message[30];
    int str_len;

    if (argc != 3)
    {
        printf("Usage : %s <IP> <port> \n", argv[0]);
        exit(1);
    }

    sock = socket(PF_INET, SOCK_STREAM, 0);
    if (sock == -1)
    {
        error_handling(("socket() error"));
    }

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);
    serv_addr.sin_port = htons(atoi(argv[2]));

    if (connect(sock, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) == -1)
        error_handling("connect() error!");

    str_len = read(sock, message, sizeof(message) - 1);
    if (str_len == -1)
        error_handling("read() error");

    str_len = read(sock, message, sizeof(message) - 1);

    if (str_len == -1)
        error_handling("read() error");

    printf("Message from server: %s \n", message);

    close(sock);
    return 0;
}
#elif _WIN32
void ErrorHandling(char* message) {
    fputs(message, stderr);
    fputc('\n', stderr);
    exit(1);
}

int client(int argc, char* argv[]) {
    WSADATA wsaData;
    SOCKET hSocket;
    SOCKADDR_IN servAddr;

    char message[30];
    int strLen;
    if (argc != 3) {
        printf("Usage : %s <IP> <port>\n", argv[0]);
        exit(1);
    }
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
        ErrorHandling("WSAStartup() error");

    hSocket = socket(PF_INET, SOCK_STREAM, 0);
    if (hSocket == INVALID_SOCKET)
        ErrorHandling("socket() error");

    memset(&servAddr, 0, sizeof(servAddr));
    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.s_addr = inet_addr(argv[1]);
    servAddr.sin_port = htons(atoi(argv[2]));

    if(connect(hSocket, (SOCKADDR*) &servAddr, sizeof(servAddr)) == SOCKET_ERROR)
        ErrorHandling("connect() error");

    strLen = recv(hSocket, message, sizeof(message) - 1, 0);
    if (strLen == -1)
        ErrorHandling("read() error");
    printf("Message from server: %s \n", message);

    closesocket(hSocket);
    WSACleanup();
    return 0;
}
#endif


int server(int argc, char* argv[])
{
    int serv_sock, clnt_sock;

    struct sockaddr_in serv_addr;
    struct sockaddr_in clnt_addr;
    socklen_t clnt_addr_size;

    char message[]="hello, world";
    if (argc!=2)
    {
        printf("Usage : %s <port> \n", argv[0]);
        exit(1);
    }

    serv_sock = socket(PF_INET, SOCK_STREAM, 0);
    if (serv_sock == -1)
        error_handling("socket() error");

    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);
    serv_addr.sin_port = htons(atoi(argv[1]));

    if (bind(serv_sock, (struct sockaddr*) &serv_addr, sizeof(serv_addr)) == -1)
        error_handling("bind() error");

    if (listen(serv_sock, 5) == -1)
        error_handling("listen() error");

    clnt_addr_size = sizeof(clnt_addr);
    clnt_sock = accept(serv_sock, (struct sockaddr*) &clnt_addr, &clnt_addr_size);
    if (clnt_sock == -1)
        error_handling("accept() error");

    write(clnt_sock, message, sizeof(message));
    close(clnt_sock);
    close(serv_sock);

    return 0;
}

int main(int argc, char* argv[])
{
    printf("Hello World.\r\n");
}